Advancements in semiconductor technology have led to miniaturized semiconductor devices. However, further miniaturization of semiconductor devices poses scaling challenges, particularly in the fabrication of the semiconductor devices. For example, the miniaturization of semiconductor devices may be limited by process and design rules.
The scaling challenges will be briefly described with reference to FIG. 1, which shows a cross-section view of a conventional semiconductor device in the prior art.
As shown in FIG. 1, the conventional semiconductor device may include an active region 103 and one or more isolation regions 105/107 formed in a substrate 101. Agate structure may be formed on a portion of the active region 103. The gate structure may include a gate insulation layer 109, a gate 111, and one or more spacers 113.
As further shown in FIG. 1, silicide layers 121 and 123 may be formed on exposed surfaces of the active region 103. A silicide layer 125 may also be formed on a top surface of the gate 111.
An insulation layer 115 may be formed over the substrate 101, and contact holes may be formed through the insulation layer 115 to the silicided active region 103 and gate 111. Contacts 117 may then be formed in the contact holes, so as to enable electrical connectivity to the silicided active region 103 and gate 111.
In semiconductor device scaling, it is desirable to increase device density by increasing the number of devices within a given area. This may be achieved, for example, by reducing the distances X1 and X2 between the respective groove isolation regions 105/107 and edges of the gate 111 (shown in FIG. 1).
Before the distances X1 and X2 may be reduced, the following dimensions need to be first taken into consideration: (1) a lateral size of each spacer 113, (2) a lateral size of each contact hole (or contact 117), and (3) a distance from each contact hole (or contact 117) to the respective groove isolation regions 105/107. The above dimensions determine the minimum “coverage” of the contacts 117 over the active region 103, as required by contact-to-active region design rules.
As a result, reductions in the distances X1 and X2 may be constrained by process and design rules. For example, due to restrictions imposed by gate current leakage, etc., the lateral size of the spacers 113 may not be reduced below a minimum size. Additionally, the process and design rule limitations may require certain minimum dimensions for the size of the contact holes (or contacts 117) and/or the distances from the contact holes (or contacts 117) to the respective groove isolation regions 105/107.
In some instances, although the dimensions X1 and X2 may be reduced using advanced reticle technologies (in lithography and etching), these next-generation semiconductor process technologies may be costly, and therefore may not provide a cost-effective solution in further miniaturization of semiconductor devices.